Omega Centauri Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Omega Centauri Observatory clear sky chart from 2005-11-05 to 2017-10-31.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
58%
15137
23%
47392
19%
15093
63%
15093
30%
28415

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
41%
720
26%
2148
13%
716
52%
716
30%
1303
January16th to endNight
37%
768
26%
2304
15%
768
46%
768
26%
1473
February1st to 15thNight
40%
704
27%
2112
13%
701
50%
701
31%
1288
February16th to endNight
35%
631
23%
1893
12%
631
43%
631
27%
1216
March1st to 15thNight
42%
654
23%
2094
14%
654
50%
654
24%
1329
March16th to endNight
52%
576
25%
2019
20%
576
60%
576
31%
1108
April1st to 15thNight
50%
539
25%
1797
20%
539
59%
539
29%
1047
April16th to endNight
56%
540
27%
1800
24%
540
64%
540
36%
961
May1st to 15thNight
65%
539
21%
1799
21%
539
69%
539
32%
1018
May16th to endNight
70%
562
21%
1855
21%
561
74%
561
32%
1054
June1st to 15thNight
77%
540
13%
1620
15%
540
78%
540
32%
996
June16th to endNight
77%
540
15%
1587
16%
540
77%
540
29%
1008
July1st to 15thNight
82%
510
14%
1566
16%
510
82%
510
30%
978
July16th to endNight
77%
564
10%
1772
13%
531
76%
531
24%
1141
August1st to 15thNight
83%
539
12%
1788
16%
536
84%
536
30%
1083
August16th to endNight
73%
573
13%
1910
16%
573
73%
573
23%
1240
September1st to 15thNight
70%
540
21%
1800
22%
540
72%
540
26%
1124
September16th to endNight
74%
702
27%
1965
24%
702
75%
702
35%
1194
October1st to 15thNight
71%
720
31%
2045
26%
720
74%
720
46%
1098
October16th to endNight
60%
768
36%
2304
29%
768
67%
768
42%
1222
November1st to 15thNight
60%
700
33%
2140
28%
700
66%
700
37%
1196
November16th to endNight
52%
720
31%
2340
25%
720
61%
720
35%
1284
December1st to 15thNight
45%
720
24%
2340
19%
720
52%
720
26%
1431
December16th to endNight
37%
768
20%
2394
14%
768
44%
768
21%
1623

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
11%5%25%5%35%5%6%8%38%
48310
Night
10%42442445%8%47%
47607
TransparencyDay
39%8%11%17%15%6%
48028
Night
33%7%13%19%17%8%
47394
SeeingDay
12%314%23%27%17%
5337
Night
12%418%29%27%8%
15139

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
15%425%5%245%5%6%43%
1790
16th to endDay
20%42432333445%
1920
February1st to 15thDay
13%5%24422347%47%
1750
16th to endDay
16%5%35%433447%41%
1580
March1st to 15thDay
17%6%25%424445%42%
1875
16th to endDay
12%5%25%425%45%8%43%
2202
April1st to 15thDay
13%5%34435%6%6%8%39%
2151
16th to endDay
11%5%25%435%46%8%41%
2160
May1st to 15thDay
12%425%5%345%6%8%41%
2151
16th to endDay
9%5%35%6%36%6%5%9%38%
2253
June1st to 15thDay
8%6%26%7%5%8%7%7%11%29%
2340
16th to endDay
6%5%27%9%5%8%7%8%11%27%
2359
July1st to 15thDay
9%6%47%8%5%8%7%7%9%25%
2295
16th to endDay
8%6%47%8%5%8%8%9%10%21%
2276
August1st to 15thDay
8%7%37%8%48%8%7%11%24%
2160
16th to endDay
11%6%36%8%5%9%7%6%8%25%
2292
September1st to 15thDay
11%6%25%6%47%6%7%9%32%
2160
16th to endDay
8%425%6%47%5%6%8%39%
1982
October1st to 15thDay
6%4144345%47%54%
1912
16th to endDay
7%213433447%56%
1919
November1st to 15thDay
9%5%24223347%54%
1716
16th to endDay
9%413314345%56%
1620
December1st to 15thDay
14%7%34423446%43%
1620
16th to endDay
20%7%35%5%345%46%34%
1827
January1st to 15thNight
14%5%24423446%47%
2148
16th to endNight
20%5%2332443446%
2304
February1st to 15thNight
13%5%2432245%6%48%
2103
16th to endNight
18%6%25%223346%44%
1893
March1st to 15thNight
15%5%15%4345%47%42%
2094
16th to endNight
12%42322335%6%53%
2019
April1st to 15thNight
11%5%3442435%7%48%
1797
16th to endNight
8%31332345%9%52%
1800
May1st to 15thNight
7%414425%5%6%9%48%
1799
16th to endNight
5%32443446%11%48%
1854
June1st to 15thNight
5%3235%36%5%8%13%42%
1620
16th to endNight
6%3235%46%5%7%11%43%
1587
July1st to 15thNight
3333435%6%8%13%43%
1659
16th to endNight
5%325%6%36%7%9%14%35%
1892
August1st to 15thNight
33145%36%7%9%14%41%
1800
16th to endNight
7%426%5%45%6%7%12%36%
1910
September1st to 15thNight
7%325%5%35%6%6%10%42%
1800
16th to endNight
6%5%145%245%5%9%48%
1965
October1st to 15thNight
4422313347%60%
2045
16th to endNight
10%313312345%60%
2304
November1st to 15thNight
9%41342335%6%55%
2140
16th to endNight
9%31333344456%
2340
December1st to 15thNight
13%5%25%424347%45%
2340
16th to endNight
20%6%35%423447%37%
2394

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
40%5%7%15%21%10%
1791
16th to endDay
42%45%16%20%9%
1920
February1st to 15thDay
36%5%9%16%22%10%
1752
16th to endDay
42%47%17%20%8%
1580
March1st to 15thDay
42%47%20%18%6%
1875
16th to endDay
38%5%9%19%21%6%
2204
April1st to 15thDay
37%8%9%18%17%7%
2151
16th to endDay
37%7%10%22%17%4
2160
May1st to 15thDay
37%7%10%21%15%7%
2151
16th to endDay
38%9%12%22%16%2
2257
June1st to 15thDay
42%11%14%20%9%1
2340
16th to endDay
45%10%17%17%8%
2359
July1st to 15thDay
46%14%17%15%4
2159
16th to endDay
48%14%19%14%2
2133
August1st to 15thDay
46%13%18%15%5%
2148
16th to endDay
48%14%14%13%6%2
2292
September1st to 15thDay
41%12%14%16%10%4
2160
16th to endDay
36%8%13%18%16%6%
1982
October1st to 15thDay
26%6%9%18%22%14%
1912
16th to endDay
26%46%14%28%19%
1919
November1st to 15thDay
29%47%17%30%9%
1716
16th to endDay
28%46%18%26%15%
1620
December1st to 15thDay
39%5%8%20%18%6%
1620
16th to endDay
49%6%6%16%16%4
1827
January1st to 15thNight
36%49%15%23%11%
2148
16th to endNight
42%35%14%23%10%
2304
February1st to 15thNight
36%47%18%21%12%
2112
16th to endNight
41%46%15%19%12%
1893
March1st to 15thNight
40%6%7%15%22%6%
2094
16th to endNight
31%412%19%23%7%
2019
April1st to 15thNight
34%5%10%22%16%10%
1797
16th to endNight
27%5%12%25%20%7%
1800
May1st to 15thNight
30%7%13%23%19%5%
1800
16th to endNight
29%9%15%26%17%1
1856
June1st to 15thNight
30%10%20%26%10%
1620
16th to endNight
32%11%23%21%10%
1587
July1st to 15thNight
28%15%28%22%5%
1566
16th to endNight
33%15%28%20%2
1772
August1st to 15thNight
26%15%30%20%5%
1788
16th to endNight
37%12%25%15%6%3
1910
September1st to 15thNight
35%10%17%16%13%6%
1800
16th to endNight
30%8%16%20%16%7%
1965
October1st to 15thNight
23%5%12%21%21%16%
2045
16th to endNight
26%35%15%27%21%
2304
November1st to 15thNight
30%37%17%28%12%
2140
16th to endNight
29%5%5%18%22%19%
2340
December1st to 15thNight
38%5%9%20%19%6%
2340
16th to endNight
47%5%6%18%15%6%
2394

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
18%5%38%22%14%
90
16th to endDay
23%18%40%14%2
96
February1st to 15thDay
14%13%31%32%7%1
90
16th to endDay
13%11%40%25%8%
81
March1st to 15thDay
23%7%42%24%2
90
16th to endDay
14%9%22%31%20%
188
April1st to 15thDay
16%8%26%26%19%2
270
16th to endDay
14%5%20%30%24%4
270
May1st to 15thDay
13%422%27%26%5%
288
16th to endDay
11%213%29%26%16%
331
June1st to 15thDay
16%6%22%27%26%
315
16th to endDay
10%16%24%35%22%
438
July1st to 15thDay
7%15%19%35%30%
433
16th to endDay
9%212%36%38%
326
August1st to 15thDay
11%1411%35%36%
313
16th to endDay
9%26%15%34%31%
332
September1st to 15thDay
11%110%21%32%23%
315
16th to endDay
11%5%23%42%16%
314
October1st to 15thDay
5%13%31%33%14%
247
16th to endDay
11%421%37%18%6%
144
November1st to 15thDay
26%120%31%16%4
90
16th to endDay
7%11%35%25%15%4
90
December1st to 15thDay
17%8%37%23%10%2
90
16th to endDay
34%7%21%22%11%2
96
January1st to 15thNight
17%6%30%36%9%
720
16th to endNight
22%8%27%32%8%
768
February1st to 15thNight
16%7%33%31%10%
704
16th to endNight
20%7%32%33%5%
631
March1st to 15thNight
17%8%27%35%11%
654
16th to endNight
13%6%22%36%20%
576
April1st to 15thNight
14%425%34%19%1
539
16th to endNight
11%324%37%22%2
540
May1st to 15thNight
9%215%42%27%2
540
16th to endNight
7%11%32%39%8%
563
June1st to 15thNight
8%425%50%12%
540
16th to endNight
6%418%46%22%
540
July1st to 15thNight
5%212%50%29%
510
16th to endNight
4214%45%31%
564
August1st to 15thNight
4210%46%35%
539
16th to endNight
9%214%44%27%
573
September1st to 15thNight
9%15%16%45%22%
540
16th to endNight
10%5%30%45%7%
702
October1st to 15thNight
6%114%35%34%7%
720
16th to endNight
11%420%32%26%4
768
November1st to 15thNight
10%419%38%22%5%
700
16th to endNight
10%6%25%37%17%1
720
December1st to 15thNight
14%7%27%33%15%
720
16th to endNight
22%8%26%30%11%
768
Page generated at 2017-11-01 16:23:32. Version ac04

Copyright 2017 A. Danko


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